A fracture dislocation of the ankle. This type of fracture usually results from the foot being caught while the body is moving forward (for example, during walking or skiing). As a result, the foot is twisted outward, producing a spiral fracture at the lower end of the fibula (the bony prominence felt on the outer side of the ankle).

This type of fracture is treated by immobilization in a plaster cast from below the knee to the base of the toes; the cast usually is left in position for about six weeks. However, more severe twisting can pull a flake of bone from the inner side of the ankle and also fracture the bottom of the tibia, or shinbone. In such cases the bones have to be realigned under anesthesia and sometimes held in place with screws; the plaster cast is left is position for up to three months.